The present invention relates to a polyarylene sulfide resin composition to be molded into precision members. Precisely, it relates to such a resin composition to be molded into precision members, which is favorable to optical communication members such as optical fiber connector ferrules and others and also to optical pickup members, etc.
Silica-containing epoxy resin compositions have heretofore been used for precision members such as optical fiber connector ferrules and others in the field of optical communication. However, the epoxy resin compositions require long molding cycles, and recycling them is difficult. These problems with them are peculiar to thermosetting resins.
Substitutable for them, thermoplastic polyarylene sulfide (PAS) resin compositions have been proposed. For example, in Japanese Patent Laid-Open No. 196208/1982, proposed is a PAS resin composition containing a spherical silica filler; and in Japanese Patent Laid-Open No. 299072/1994, proposed is a PAS resin composition containing silica, in which the filler, silica is subjected to surface treatment with a silane coupling agent. In PCT patent document No. WO95/25770, proposed is a PAS resin composition containing whiskers and spherical silica.
However, the resin compositions proposed are still unsatisfactory with respect to the balance of dimensional accuracy and mechanical strength.
The present invention is to provide a polyarylene sulfide resin composition which has the advantages of well-balanced physical properties, dimensional accuracy and mechanical strength, and good moldability, and is therefore favorable to moldings for precision members such as optical fiber connector ferrules and others.
In our studies of polyarylene sulfide resin compositions that are directed to improving the balance of the dimensional accuracy, the mechanical strength and the moldability of the resin compositions, especially to improving the dimensional accuracy thereof, we, the present inventors have found that, when the amount of whiskers which are effective for reinforcement but are unsatisfactory for dimensional accuracy improvement is reduced in the resin compositions and when, in place of it, the amount of a polyarylene sulfide having a specific melt viscosity and the amount of spherical silica having a specific particle size are increased therein, then the intended object can be attained. On the basis of this finding, we have completed the present invention disclosed herein.
Specifically, the invention is summarized as follows:
(1) A polyarylene sulfide resin composition comprising (A) from 20 to 34% by weight of a polyarylene sulfide having a melt viscosity of from 150 to 800 poises at 300xc2x0 C. in terms of the resin temperature and at a shear rate of 500 secxe2x88x921, (B) from 66 to 80% by weight of spherical silica having a mean particle size of from 0.3 to 10 xcexcm, and (C) from 0 to 12% by weight of whiskers, in which the total of the spherical silica (B) and the whiskers (C) falls between 66 and 80% by weight.
(2) A polyarylene sulfide resin composition comprising (A) from 22 to 28% by weight of a polyarylene sulfide having a melt viscosity of from 150 to 800 poises at 300xc2x0 C. in terms of the resin temperature and at a shear rate of 500 secxe2x88x921, (B) from 72 to 78% by weight of spherical silica having a mean particle size of from 0.3 to 10 xcexcm, and (C) from 0 to 6% by weight of whiskers, in which the total of the spherical silica (B) and the whiskers (C) falls between 72 and 78% by weight.
(3) A polyarylene sulfide resin composition, of which the tabular moldings formed to have through-holes running through their cross section are such that the circularity of the through-holes is at most 1.8 xcexcm, the coefficient of thermal expansion of the moldings (both in MD and TD) is at most 1.8xc3x9710xe2x88x925/K, and the flexural strength of the moldings is at least 120 MPa.